BCS surrogate models for floating superconductor-semiconductor hybrids

Virgil V. Baran; Jens Paaske

doi:10.1103/PhysRevB.109.224501

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BCS surrogate models for floating superconductor-semiconductor hybrids

Virgil V. Baran, Jens Paaske

DOI 10.1103/PhysRevB.109.224501 · Physical Review B

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Abstract

Superconductor-semiconductor hybrid devices, involving quantum dots interfaced with floating and/or grounded superconductors, have reached a level of complexity, which calls for the development of versatile and numerically efficient modeling tools. Here, we propose an extension of the surrogate model solver for subgap states [Phys. Rev. B 108, L220506 (2023)], which is able to handle floating superconducting islands with finite-charging energy. Upon eliminating all finite-size effects of the computationally demanding Richardson model approach, we achieve a more efficient way of calculating the subgap spectra and related observables without compromising their accuracy. We provide a number of benchmarks between the two approaches and showcase the versatility of the extended surrogate model solver by studying the stability of spin-triplet ground states in various tunable devices. The methods introduced here set the stage for reliable microscopic simulations of complex superconducting quantum circuits across all their relevant parameter regimes.